This invention relates generally to medical and dental implant devices and more particularly to a method for transferring the relative position of an intra-osseous implant relative to a laboratory replicated position, as in a dental abutment, and for determining the appropriate height of a dental abutment received in an implant for an aesthetic submucosal prosthetic margin placement.
Implant systems comprising an implant having a tapered bore adapted to receive therein an abutment post or the like formed with a matching taper for retention of the post in the implant are known. See for example U.S. Pat. No. 4,738,623, assigned to the assignee of the present invention, the disclosure of which is incorporated herein by this reference. It is also known to provide such posts, which are intended to be used as impression posts or temporary abutment posts, with a longitudinally extending slot in the end thereof in order to more easily remove the posts. Generally, such posts are made of titanium or titanium alloy due to their biocompatibility characteristics. However, titanium has a major limitation relating to the phenomenon of memory. It is possible for the diameter of the slotted post to either widen or narrow over time making the nature of the fit of the post in an abutment unpredictable. The property of memory can cause an abutment to become loose in clinical function and result in an unpredictable degree of retention.
There is a need to be able to replicate the position that an abutment would have in an implant in a system using abutment analogs, impression posts and the like made of the same or different materials which accurately and reliably correspond to the locked position of a permanent abutment in an intra-osseous implant. Among the factors which need to be dealt with in doing this is the existence of hydraulic pressure resisting the seating of a post as well as the need for having the post retain its seated position whether gravity is adding a force against seating or toward seating, as in the use in upper teeth versus lower teeth. There is also a need to be able to determine the appropriate height of an abutment which will provide an aesthetic submucosal prosthetic margin placement.
It is an object of the invention to overcome the prior art limitations noted above. Another object of the invention is the provision of an impression post and any other post, such as a temporary abutment post, wherein a clinician will want to remove the post with minimal, predictable effort.
Briefly, in accordance with one embodiment of the invention, the post of a member, such as an abutment analog, impression post, implant transport handler, healing plug and the like, is formed with a radially outwardly extending stop surface such as a shelf having a diameter larger than the diameter of the bore in a permanent implant and an implant analog and located at a distance from the longitudinal axial position of a reference location of a head formed on the post essentially equal to the distance from the top end surface of a permanent implant to a corresponding reference location of a head of an abutment with the abutment in a clinically locked position as a result of being tapped into the implant.
According to another embodiment, an implant analog is formed with a shelf in the bore of the implant analog located at a distance from the mouth of the bore, i.e., the top surface of the implant analog, essentially equal to the distance between the bottom end face of the tapered post of a permanent abutment and the longitudinal axial position on the tapered post at the top face surface of the permanent implant with the permanent abutment in the locked position upon receiving clinical tapping insertion force. The shelf prevents a tapered permanent abutment post from over-seating in an implant analog, which is particularly important when the implant analog is composed of plastic material. According to a feature of the invention, the cylindrical bore of the implant analog can be provided with one or more flats to increase the retention resistance of a cylindrical post, with or without a taper, received therein as well as to provide an axially extending air passage to relieve or prevent the build up of hydraulic pressure in the closed end of the bore.
According to a feature of the invention, retentive resistance of the post of the abutment analog, impression post, implant transport handler, healing plug and the like can be increased by forming one or more circumferential rings about the posts, at least one of the rings having an outer diameter larger than the diameter of an implant bore to form an interference fit and preferably, the at least one ring being flexible and having a feathered, or otherwise shaped configuration so that upon being inserted into the bore of the implant the outer peripheral portion of that ring will bend in a direction opposite to the direction of insertion so that upon removal of the post the outer peripheral portion of the ring will have to bend back on itself thereby requiring a greater removal force than insertion force.
According to yet another embodiment of the invention, an elongated probe member having a size to be freely insertable in the bore of an implant is formed with a plurality of axially positioned index configurations, such as circumferential grooves, located in the probe member at selected distances from the free distal end of the probe member corresponding to the position of given reference locations of a clinically seated abutment in the implant. The index configurations indicate the axial position of a given geometry of the implant bore as a reference point so that the appropriate height of an abutment shoulder can be determined to achieve an aesthetic submucosal prosthetic margin placement.
Additional objects and features of the invention will be set forth in part in the description which follows and in part will be obvious from the description and drawings. The objects and advantages of the invention may be realized and attained by means of the instrumentalities, combinations and methods particularly pointed out in the appended claims.